A large variety of demonstrations are possible by using the demo apparatus. Depending on the number of filters, prisms and other optical elements available to you, the LED cluster can be used to demonstrate the basic principles of colour addition, subtraction and mixing as well as many principles of general optics.  Colour Addition / Subtraction During this demonstration the LED were set to show various combinations of colours to effectively map the RGB colour gamut of the LED cluster and illustrate the concept of colour addition. This includes the boundary of the gamut as well as the interior, in particular the creation of white light through RGB combination. The subtraction part illustrates the inverse of colour addition by using the various colour filters over the base plate with all clusters illuminated. This will serve as an introduction of wave theory of light and colour-wavelength dependence. The emission-wavelength curves of the LED will be presented to illustrate the concept of bandwidth. A red laser pointer will provide an example of a very narrow bandwidth. If the basic concepts of the wave theory of light are not part of the class curriculum then a brief description of the wave model will be provided as well. Colour Dispersion Using the base and a glass prism the basic principle of refraction can be illustrated and in particular colour dispersion of the light (essentially Newton’s dispersion experiment).    Some photos of various colour mixes made with the demo appartus can be found here.